Typical fluid dispensers include a container defining therein a chamber for receiving a fluid to be dispensed, a nozzle and pump assembly mounted on the container, and a dip tube extending downwardly from the nozzle into the chamber for pumping the fluid from the bottom of the chamber, through the dip tube, and out of the dispenser. Other known dispensers include a vial and a flexible bladder received within the vial. For example, U.S. Pat. No. 6,062,430 to Fuchs shows in FIG. 1 a dispensing container with variable volume compensation including a bottle-shaped vessel 2 in the form of a thin-walled, hollow body made from soft elastic plastic, and a reception container 15 formed of a wrinkle film encapsulated within the vessel body 2.
One of the drawbacks associated with typical prior art fluid dispensers is that the fluid chamber(s) are not maintained in a substantially airless condition throughout the storage, shelf life and/or usage of the dispenser. For example, the nozzles and/or valves used in typical prior art dispensers frequently are incapable of maintaining the dispenser in a hermetically sealed condition. Such nozzles and/or valves allow the passage of air or other gases therethrough and into contact with the medicament or other substance contained within the fluid chamber(s). In addition, such nozzles and/or valves frequently allow vapor loss therethrough either during the storage, shelf life or usage of the dispensers.
Another drawback associated with prior art dispensers is that the materials of construction may undergo creep that, in turn, causes seals formed within the dispensers to leak. Many medicaments are maintained in storage and/or on store shelves for at least several, and in some instances, many months. During transportation and storage, the dispensers can be subjected to varying atmospheric conditions involving large variations in atmospheric temperature, pressure and/or humidity. As a result, the dispensers are frequently subjected to substantial differential thermal expansion and/or contraction that, in turn, cause the materials of construction to undergo creep. The seals and other components of such prior art dispensers typically are not designed to address such creep, and as a result, the dispensers develop leaks or otherwise allow air ingress and/or vapor loss when subjected to such long periods of storage or varying atmospheric conditions. For example, some polyethylene dispensers have been known to lose between about 10% to 25% of the weight of their contents during storage. Such weight loss is believed to be due to vapor loss from the medicament or other fluid-containing chambers through the polyethylene walls of the dispensers and/or through leaks otherwise created in the seals or other structural interfaces of the containers. The vapor loss is typically offset by air ingress into the chambers. Vapor loss and/or air ingress is particularly problematic for dispensers containing medicaments, such as pharmaceutical preparations or vaccines, because they tend to dilute each predetermined dosage of the medicament dispensed from the container, and/or cause the dispenser to dispense inconsistent concentrations of medicament from one dose to the next.
Yet another disadvantage associated with prior art dispensers is that because they cannot reliably maintain the medicament or other substance contained therein in an airtight condition, they cannot be used for either multiple dose applications or preservative-free formulations. The use of single dose dispensers can be substantially more expensive than multiple dose dispensers. In addition, the preservatives used in many medicaments, such as pharmaceutical preparations and vaccines, can cause adverse reactions in patients and/or dilute the effect of the medicament on the patient.
Another drawback of prior art dispensers is that the ullage or “dead space” inherent in such dispensers allows sediment build-up. Many medicaments and other formulations contained within such dispensers are suspensions. The ullage or dead space in the prior art dispensers allows the solutes or other solid components of such suspensions to form sediment therein. Such settling of the suspensions dilutes the medicaments or other substances contained within the dispensers and, in turn, alters the medicament and/or the concentration of medicament in each patient dose.
Another drawback associated with many prior art dispensers is that they can only dispense the medicament or other substance contained therein in an upright or other single orientation. This drawback prevents such dispensers from being used effectively in other orientations, such as upside down. In addition, because such dispensers do not maintain the medicament or other substance contained therein in an airless condition, they cannot be used in low gravity environments, such as outer space.
Accordingly, it is an object of the present invention to overcome one or more of the above-described drawbacks and disadvantages of the prior art.